In Walden (1854), Henry David Thoreau described foxes crying out "raggedly and demoniacally" as they hunted through the winter forest, and he wrote, "Sometimes one came near to my window, attracted by my light, barked a vulpine curse at me, and then retreated." Thoreau's was far from the first use of vulpine; English writers have been applying that adjective to the foxlike or crafty since at least the 15th century, and the Latin parent of our term, vulpinus (from the noun vulpes, meaning "fox"), was around long before that.
Word History
Etymology
Middle English, from Latin vulpinus, from vulpes fox; perhaps akin to Greek alōpēx fox — more at alopecia